Lifetime studies of synthetic cables subjected to lateral contact loads from sheaves

This paper presents results from a study of synthetic fiber ropes subjected to high tension and lateral loads, as would be the case when a rope passes over a drum, or supports a moving trolley along the rope. The tests were performed on representative strands using a special machine designed to duplicate the type of loading and damage to the strands as they lie in the rope. Results show that the jackets on strands increase significantly the strand lifetime, but the effects of different polymer lubricants coating the cords in a strand are not as significant as might be expected. We also found that strands made of Vectran fiber have about 10 to 15 times longer lifetimes at comparable loads than strands made of Kevlar fiber, which corresponds to about double the sheave load achieving the same lifetime. Vectran strands also have about 2 to 3 times longer lifetimes than strands made of Technora fibers at comparable loads, which corresponds to about a 25% increase in the sheave load for the same lifetime. Thus strands made of both Vectran and Technora seem to have superior abrasion resistance as compared to Kevlar strands.